1. Field of the Invention
This invention relates to a read-out apparatus for an image detector. This invention particularly relates to a read-out apparatus for reading out an electrostatic latent image from an image detector, which generates a current in accordance with latent image charges carrying image information. This invention also relates to an image detecting and read-out apparatus comprising the read-out apparatus and the image detector, which are combined with each other.
2. Description of the Prior Art
Apparatuses utilizing image detectors, e.g. facsimile apparatuses, copying machines, and radiation image sensors, have heretofore been known.
For example, systems for recording and reading out radiation image information utilizing image detectors have heretofore been proposed. With the proposed systems for recording and reading out radiation image information, such that a radiation dose delivered to an object during a medical X-ray image recording operation may be kept small, and such that the image quality of an image and its capability of serving as an effective tool in, particularly, the efficient and accurate diagnosis of an illness may be enhanced, a photo-conductive material sensitive to X-rays, such as a selenium plate constituted of, e.g., a-Se, is employed as a photosensitive material or an electrostatic recording material. The photosensitive material (or the electrostatic recording material) is exposed to radiation, such as X-rays, carrying radiation image information, and latent image charges carrying the radiation image information are thereby accumulated in the photosensitive material. Thereafter, the photosensitive material is scanned with a laser beam, and currents occurring in the photosensitive material are detected via flat plate-shaped electrodes or comb tooth-shaped electrodes, which are located on opposite surface sides of the photosensitive material. In this manner, the electrostatic latent image represented by the latent image charges, i.e. the radiation image information, is read out. Such systems for recording and reading out radiation image information are described in, for example, U.S. Pat. Nos. 4,176,275, 5,440,146, and 5,510,626, xe2x80x9cA Method of Electronic Readout of Electrophotographic and Electroradiographic Image,xe2x80x9d Journal of Applied Photographic Engineering, Volume 4, Number 4, Fall 1978, pp. 178-182 (hereinbelow referred to as the Literature 1), and xe2x80x9c23027 Method and device for recording and transducing an electromagnetic energy pattern,xe2x80x9d Research Disclosure, Jun. 1983 (hereinbelow referred to as the Literature 2).
With the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1, a laser beam having been produced by an argon laser is expanded into a thin line-shaped light (a line light), and the line light is focalized by a cylindrical lens onto a photosensitive material, on which an electrostatic latent image has been recorded. In this manner, the photosensitive material is mechanically scanned with the line light, and the electrostatic latent image having been recorded on the photosensitive material is read out in a parallel manner with a plurality of comb tooth-shaped electrodes.
In the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1, such that the photosensitive material, from which the electrostatic latent image has been read out, may be used again for the recording of an electrostatic latent image, it is necessary to perform an erasing process for exposing the photosensitive material to uniform erasing light. In U.S. Pat. No. 5,510,626, a system provided with means for cutting out light having wavelengths for readout (wavelengths of blue light) as a light source for producing the uniform erasing light is disclosed.
With the system described in the Literature 2, pre-charging is performed with primary exposure, and thereafter final recording is performed.
Also, in Japanese Patent Application No. 10(1998)-232824, the applicant proposed an electrostatic recording material and a read-out apparatus for reading out radiation image information from the electrostatic recording material, on which the radiation image information has been recorded. The proposed electrostatic recording material comprises:
i) a first electrical conductor layer having permeability to recording radiation,
ii) a recording photo-conductive layer, which exhibits photo-conductivity when it is exposed to the recording radiation,
iii) a charge transporting layer, which acts approximately as an insulator with respect to electric charges having a polarity identical with the polarity of electric charges occurring in the first electrical conductor layer, and which acts approximately as a conductor with respect to electric charges having a polarity opposite to the polarity of the electric charges occurring in the first electrical conductor layer,
iv) a reading photo-conductive layer, which exhibits photo-conductivity when it is exposed to a reading electromagnetic wave, and
v) a second electrical conductor layer having permeability to the reading electromagnetic wave, the layers being overlaid in this order.
With the read-out apparatus described in Japanese Patent Application No. 10(1998)-232824, the electrostatic recording material, on which an electrostatic latent image has been recorded, is scanned with a reading electromagnetic wave having been produced by a light source, and the electrostatic latent image having been recorded on the electrostatic recording material is thereby read out. Japanese Patent Application No. 10(1998)-232824 also discloses a technique for performing pre-exposure prior to the recording of the electrostatic latent image and thereby preventing image quality from becoming bad due to a residual image or a dark latent image.
However, with the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1, wherein the photosensitive material is mechanically scanned with the line light, it is necessary for the cylindrical lens for the scanning, a mechanical scanning section, and the like, to be provided. Therefore, the problems occur in that a large number of parts must be provided, and the read-out apparatus cannot be kept cheap in cost and small in size. Also, the problems occur in that scanning nonuniformity ordinarily occurs with the mechanical scanning.
Further, as described in U.S. Pat. No. 5,510,626, such that the photosensitive material, from which the electrostatic latent image has been read out, may be used again for the recording of an electrostatic latent image, the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1 must be provided with means for cutting out light having wavelengths for readout from the light having been produced by the erasing light source. Therefore, the number of necessary parts increases even further, and the problems occur in that the read-out apparatus becomes expensive and large in size.
With the system described in the Literature 2, besides the light source for readout, a light source for the primary exposure must be provided. Therefore, the problems occur in that the read-out apparatus cannot be kept cheap in cost and small in size.
In Japanese Patent Application No. 10(1998)232824, it is not described clearly whether the scanning with reading light is or is not the mechanical scanning. However, from drawings for embodiments, it is presumed that the scanning with the reading light is the mechanical scanning. In cases where the scanning is the mechanical scanning, the same problems as those encountered with the systems described in U.S. Pat. No. 4,176,275, and the like, occur.
In cases where the scanning with the reading light is the mechanical scanning, the photosensitive material or the electrostatic recording material, on which the electrostatic latent image has been recorded, must be set on the read-out apparatus, and the electrostatic latent image must be read out with the read-out apparatus. Therefore, it is difficult to combine the photosensitive material, or the like, and the read-out apparatus with each other, i.e. to form a portable type of apparatus, such that the electrostatic latent image can be read out immediately after the recording or whenever it is to be read out.
The primary object of the present invention is to provide a read-out apparatus for an image detector, wherein an electrostatic latent image is capable of being read out from a photosensitive material, or the like, without mechanical scanning being required.
Another object of the present invention is to provide an image detecting and read-out apparatus comprising a read-out apparatus and an image detector, which are combined with each other.
The present invention provides a read-out apparatus for an image detector, wherein a reading electromagnetic wave is caused to scan an image detector, on which image information has been recorded as an electrostatic latent image, and electric currents caused by the scanning to flow out of the image detector in accordance with the electrostatic latent image are detected, the read-out apparatus comprising:
i) a surface-shaped wave source constituted of a plurality of small wave sources, which are arrayed in a surface form and each of which produces the reading electromagnetic wave, and
ii) wave source control means for performing the scanning by driving the small wave sources one after another.
The term xe2x80x9cimage detectorxe2x80x9d as used herein means the device capable of recording image information as an electrostatic latent image and generating electric currents in accordance with the electrostatic latent image when being scanned with the reading electromagnetic wave. By way of example, the image detector may be the photosensitive material described in U.S. Pat. No. 4,176,275, or the like, or the Literature 1, or the electrostatic recording material described in Japanese Patent Application No. 10(1998)-232824. As the image detector, an image detector may be employed, which is capable of recording image information as an electrostatic latent image when being exposed to light (not limited to visible light) carrying the image information. Alternatively, an image detector may be employed, which is capable of recording radiation image information as an electrostatic latent image when being exposed to radiation carrying the radiation image information of an object. This also applies to an image detector of an image detecting and read-out apparatus in accordance with the present invention, which will be described later.
The reading electromagnetic wave may be one of various kinds of electromagnetic waves, with which the electrostatic latent image is capable of being read out from the image detector. Specifically, the reading electromagnetic wave may be light, radiation, or the like. Therefore, in cases where light is utilized as the reading electromagnetic wave, the wave source may be referred to as the light source. In cases where radiation is utilized as the reading electromagnetic wave, the wave source may be referred to as the radiation source.
The read-out apparatus for an image detector in accordance with the present invention should preferably be modified such that it further comprises electromagnetic shield means located at least on the side of the surface-shaped wave source, which stands facing the image detector. The electromagnetic shield means should have permeability to the reading electromagnetic wave. Besides the side of the surface-shaped wave source, which stands facing the image detector, the electromagnetic shield means should preferably be located also on other sides of the surface-shaped wave source. For example, the electromagnetic shield means should preferably be located so as to surround the entire surface-shaped wave source. In cases where the electromagnetic shield means surrounds the entire surface-shaped wave source, it is only necessary that at least the side of the electromagnetic shield means, which stands facing the image detector, has permeability to the reading electromagnetic wave, and all sides of the electromagnetic shield means need not necessarily be permeable to the reading electromagnetic wave.
Also, the read-out apparatus for an image detector in accordance with the present invention should preferably be modified such that the wave source control means is capable of simultaneously driving the plurality of the small wave sources so as to irradiate a pre-exposure electromagnetic wave to the image detector. In such cases, the plurality of the small wave sources may be driven simultaneously, and the pre-exposure electromagnetic wave may thereby be irradiated to the image detector. It is most preferable that the pre-exposure electromagnetic wave is irradiated simultaneously to the entire area of the image detector. Alternatively, for example, the pre-exposure electromagnetic wave may be irradiated to the right half of the image detector and then to the left half of the image detector.
The term xe2x80x9cpre-exposurexe2x80x9d as used herein means that the electromagnetic wave is irradiated to the image detector in order to eliminate unnecessary electric charges accumulated in the image detector before the recording light is irradiated to the image detector (as described in Japanese Patent Application No. 10(1998)-232824), or that primary exposure is performed in order to perform pre-charging before final recording is performed (as described in the Literature 2). The wavelengths of the pre-exposure electromagnetic wave may be identical with the wavelengths of the reading electromagnetic wave, or may be different from the wavelengths of the reading electromagnetic wave.
Further, the read-out apparatus for an image detector in accordance with the present invention should preferably be modified such that the plurality of the small wave sources are point-shaped small wave sources, and the surface-shaped wave source is constituted of the plurality of the point-shaped small wave sources, which are arrayed in a matrix form. Alternatively, the plurality of the small wave sources may be line-shaped small wave sources, and the surface-shaped wave source is constituted of the plurality of the line-shaped small wave sources, which are arrayed so as to stand side by side along a direction normal to a longitudinal direction of each small wave source. In such cases, the point-shaped small wave sources or the line-shaped small wave sources may be arrayed such that they may be in close contact with one another or such that they may be disposed at a predetermined spacing from one another. For example, in order for the read-out sharpness to be enhanced, the small wave sources may be disposed at a predetermined spacing from one another.
In cases where the plurality of the line-shaped small wave sources are arrayed so as to stand side by side along the direction normal to the longitudinal direction of each small wave source, each of the line-shaped small wave sources should preferably be constituted of a plurality of point-shaped small wave sources, which are arrayed in a line form. In such cases, the plurality of the point-shaped small wave sources, which constitute each line-shaped small wave source, may be arrayed such that they may be in close contact with one another or such that they may be disposed at a predetermined spacing from one another.
In the read-out apparatus for an image detector in accordance with the present invention, the surface-shaped wave source should preferably be constituted of an electroluminescence (EL) device, such as an organic EL device. Alternatively, the surface-shaped wave source may be constituted of a liquid crystal and a back light source, which is located on a side of the liquid crystal that is opposite to the side of the liquid crystal facing the image detector. Particularly, in cases where the organic EL device is employed, the organic EL device should preferably be provided with a dielectric multi-layer film, which is located on the side facing the image detector.
The present invention also provides an image detecting and read-out apparatus, comprising:
i) an image detector, which records image information as an electrostatic latent image and which generates electric currents in accordance with the electrostatic latent image when it is scanned with a reading electromagnetic wave,
ii) current detecting means for detecting the electric currents generated by the image detector,
iii) a surface-shaped wave source constituted of a plurality of small wave sources, which are arrayed in a surface form and each of which produces the reading electromagnetic wave, and
iv) wave source control means for performing the scanning by driving the small wave sources one after another,
the image detector, the current detecting means, the surface-shaped wave source, and the wave source control means being combined with one another.
As the surface-shaped wave source constituting the image detecting and read-out apparatus in accordance with the present invention, one of various examples of the surface-shaped wave source constituting the aforesaid read-out apparatus for an image detector in accordance with the present invention may be employed. In such cases, the surface-shaped wave source should preferably take on the form adapted to the form of reading electrodes of the image detector (e.g., the flat plate-shaped electrode or the comb tooth-shaped electrodes). For example, in cases where the image detector has the comb tooth-shaped electrodes, the surface-shaped wave source should preferably be constituted of a plurality of line-shaped small wave sources, which are arrayed so as to stand side by side along the direction normal to the longitudinal direction of each small wave source.
Also, in the image detecting and read-out apparatus in accordance with the present invention, the electromagnetic shield means described above should preferably be utilized. Further, the wave source control means should preferably be capable of simultaneously driving the plurality of the small wave sources so as to irradiate a pre-exposure electromagnetic wave to the image detector.
Specifically, the image detecting and read-out apparatus in accordance with the present invention comprises the image detector and the read-out apparatus, which are combined with each other, and the aforesaid features of the read-but apparatus for an image detector in accordance with the present invention may also be employed in the image detecting and read-out apparatus in accordance with the present invention.
With the read-out apparatus for an image detector in accordance with the present invention, the plurality of the small wave sources are arrayed in a surface form and driven one after another. In this manner, the image detector is scanned with the reading electromagnetic wave. Therefore, it is unnecessary for mechanical scanning as in conventional techniques to be performed for the scanning with the reading electromagnetic wave. As a result, the number of parts can be kept small, and a simple, cheap, and small read-out apparatus can be formed. Also, since the mechanical scanning is not performed, the scanning system need not be provided with movable parts. Accordingly, the reliability of the read-out apparatus can be enhanced, and scanning nonuniformity can be reduced.
Further, with the read-out apparatus for an image detector in accordance with the present invention, wherein the electromagnetic shield means is located at least on the side of the surface-shaped wave source, which stands facing the image detector, the problems can be prevented from occurring in that noise appears on the read-out image due to electromagnetic noise occurring when the small wave sources are changed over and driven one after another.
Furthermore, with the read-out apparatus for an image detector in accordance with the present invention, wherein the irradiation of the pre-exposure electromagnetic wave to the image detector is performed by utilizing the reading wave source and by simultaneously driving the plurality of the small wave sources, the reading wave source can be utilized also as the pre-exposure wave source. Therefore, the number of parts of the apparatus can be kept small, and a cheap and small apparatus can be formed.
Also, in cases where the plurality of the small wave sources are arrayed in a surface form, for example, the plurality of the point-shaped may be arrayed in a matrix form, or the plurality of the line-shaped small wave sources may be arrayed so as to stand side by side along the direction normal to the longitudinal direction of each small wave source. Therefore, the constitution of the small wave sources can be selected appropriately in accordance with the form of the reading electrodes of the image detector (e.g., the flat plate-shaped electrode or the comb tooth-shaped electrodes). Particularly, in cases where the plurality of the line-shaped small wave sources are arrayed so as to stand side by side along the direction normal to the longitudinal direction of each small wave source, each of the line-shaped small wave sources may be constituted of a plurality of point-shaped small wave sources, which are arrayed in a line form. In such cases, quick readout can be performed (by virtue of the utilization of the line-shaped small wave sources), and the read-out sharpness can be enhanced.
As the surface-shaped wave source, specifically, the EL device, such as an organic EL device, or the liquid crystal may be utilized. The EL device and the liquid crystal are currently available easily. Therefore, the read-out apparatus for an image detector in accordance with the present invention can be produced easily. In particular, in cases where the organic EL device, which is provided with the dielectric multi-layer film located on the side facing the image detector, is utilized, the directivity of the EL light can be enhanced, and the read-out sharpness can be enhanced.
Further, in cases where the image detector, the current detecting means, the surface-shaped wave source, and the wave source control means are combined with one another, the apparatus can be formed as a portable type of apparatus, with which the electrostatic latent image can be read out immediately after the recording or whenever it is to be read out.